Sterner B, Abrahamsson M, Sjostrom A. The effects of accommodative facility training on a group of children with impaired relative accommodation--a comparison between dioptric treatment and sham treatment. Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists). 2001;21(6):470-6. http://www.ncbi.nlm.nih.gov/pubmed/11727875